Surgery for kidney stones is traumatic to the patient in general, and specifically to the kidney operated upon. Typically, a kidney will withstand no more than three such surgical operations without shutting down. Extracorporeal shockwave lithotripters have in most cases rendered such surgery unnecessary. As is known, an ellipsoid of revolution has two focal points. A reflector comprises a truncated ellipsoid which has a pair of electrodes spaced apart to define a sparkgap precisely at the first focus point of the ellipsoid. A rubber or the like diaphragm covers the truncated, open end of the ellipsoidal reflector. The reflector is filled with water having a sufficient saline content to make it conductive. The reflector is positioned with the diaphragm at the end thereof against the patient's body such that the second focus point of the ellipsoidal reflector lies precisely on the kidney stone to be disintegrated. High voltage electrical pulses generate a series of sparks in the gap between the electrodes. Each such spark flashes a certain amount of water into steam, and may actually dissociate a certain amount of the water. A shockwave is generated which is reflected by the ellipsoidal reflector to focus precisely on the kidney stone. The shockwave energy passes through the water in the reflector, through the diaphragm, and through human tissue which is mostly water. Within an hour the kidney stone is usually reduced to fine particles that pass from the body along with the urine.
Such extracorporeal lithotripters are quite expensive, often measured in millions of dollars. This limits availability of such lithotripters to large hospitals and the like having sufficient capital to finance purchase of such lithotripters. In addition to the cost, most such lithotripters are interconnected with computers to effect positioning of the reflector and to control operation of the lithotripter. Many physicians are unfamiliar with computers and are somewhat "put off" in having/to use computer controlled devices.
Some of the prior art extracorporeal lithotripters have required that the patient and the reflector be immersed in a rather large water bath. Those that have not required immersion have generally required that the patient lie on his back on a table having a hole or recess therein to permit the reflector to approach his back from below. Electrical or electrical/mechanical devices of considerable complexity and cost have generally been required for proper positioning of the lithotripter reflector adjacent the patient's body.